Collagen sponges or foams have been used as hemostatic agents and more recently as scaffolds for tissue repair in vivo and as research tools in vivo for seeding various cell types to study cell functions in three dimensions. Collagen sponges have a low immunogenicity and consist of a naturally occurring structural protein to which cells can attach, interact with and degrade. In vivo they are bioabsorbable. However, sponges are usually crosslinked to provide the degree of wet strength and measured resistance to dissolution needed for many of the above-referenced uses. In general, crosslinking reduces or degrades the normal binding sites seen by other molecules and cells in cell and tissue interactions with the extracellular matrix that surrounds cells. Further, collagen sponges, gelatin sponges or polyvinyl alcohol sponges lack biological activity typically present in the extracellular matrix environment of cells. However, because of their deficiencies, crosslinked collagen sponges induce little regeneration in vitro or serve poorly as histiotypic and organotypic models in vitro.
A need exist, therefore, for an improved biopolymer foam that overcomes or minimizes the above-mentioned problems.